ATLANTA — Tonya Jones doesn't want to imagine what it would feel like to have a black president in the White House.

"I want to feel that euphoria, but I can't," said Jones, an African American hairstylist who was hanging out in front of her shop here on a slow afternoon. "Because I don't want to put myself way up here" -- with this she raised her hand over her head -- "only to fall." She let her hand plunge downward like a falling elevator.

"Everybody's on edge, I'm telling you," she said.

Such are the fraught emotions of African Americans, whose up-from-slavery story could culminate Nov. 4 in the election of a black president. Polls show that black voters overwhelmingly support Barack Obama in the presidential race, in many cases for reasons that transcend policy: One popular T-shirt depicts Obama with the Rev. Martin Luther King Jr. under the banner "A Dream Answered."

But many blacks are also steeling themselves for the heartbreak that will come if a breakthrough does not. Damascus Harris, a school administrator in Chicago, rattled off a litany of past indignities his people have suffered -- from the broken promises that followed slavery to Jim Crow-era voter suppression to racist redlining by banks. They explained, in part, why Harris won't be surprised if Obama loses this election.

"I'm not naive about what our history has been," he said.

That skepticism, born of centuries of experience, is shaping the mood of the black electorate on the eve of this historic election. Even with Obama surging in national polls, the excitement of his black supporters is in many cases tempered by an acute anxiety.

"I've seen lots of moods around rage and progress and all those things," said Andrea Y. Simpson, a political science professor at the University of Richmond who marched with King when she was a girl. "This is the strangest one I've experienced . . . of anticipation, hope, pride -- and fear."

Fear finds its most intense expression in the ongoing concerns for Obama's safety. Rosalind Johnson, a finance company worker from Camden, S.C., stated her deepest worry bluntly, as if it were a fact: "He will be assassinated," she said on a sunny weekday morning recently as she walked out of her local registrar's office.

There are other, less morbid concerns. Some voters fret over the shadowy workings of a system that they believe will prevent Obama from ascending to the highest office in the land. Sometimes this conversation hinges on the voting irregularities of the 2000 election. Sometimes the sentiment is more vague.

"It's going to be something," said Tony Gonzales, an Atlanta barber. "Because it's a black person, something's going to happen."

Shan Dennis, a worker at a Decatur, Ga., insurance company, said she isn't worried about a fix being in -- but she says it's something she hears about quite a bit.

"That's been a big [issue] in the African American community," she said. "A lot of them think someone is not going to let him win."

Other voters are dismayed by the ugly tone that has emerged in the last few months, as Obama's candidacy unearthed frank expressions of prejudice from white voters, and polls show some of them may be resistant to the idea of a black president: One AP-Yahoo News poll in September suggested that a third of white Democrats held negative views toward blacks.

The Rev. Kevin M. Turman, pastor of the Second Baptist Church of Detroit, has seen similar polls. He grows worried and frustrated when he thinks of the scenario they could trigger.

"My concern is that white Democrats -- who agree with Obama on every issue -- won't vote for him because he's black," Turman said.

Historically, Turman said, black voters have proved one of the most reliable constituencies for the Democratic Party. If whites don't show up to vote for a qualified black candidate, he would feel something like betrayal.

"I will have to reconsider my lifelong support of the Democratic Party," he said. "Perhaps it will be time for us to look at elections on more of a candidate-by-candidate basis, and not just vote the party ticket."

Obama's father was a black Kenyan; his mother was a white Kansan; and he was raised by white grandparents. The election, of course, is about many things, not just racial identity. And black voters have different opinions about whether the election should be viewed as a referendum on the state of American race relations.

The Rev. Joseph Lowery, a civil rights veteran and co-founder of the Southern Christian Leadership Conference, thinks the matter is plain:

"What we boil down to is a choice between 'Will you vote for the good of the country?' or 'Will you vote your racial fears?' " said Lowery.

But Charles Johnson, a novelist and English professor at the University of Washington, said it may be difficult to draw hard and fast conclusions about race relations from the November vote.